Inflammation is a complex biological response of vascular tissue to harmful stimuli, such as oxidative stress, irritants, pathogens, and damaged cells. It is a protective attempt by the organism to remove an injurious stimulus and initiate the healing process for injured tissue. The inflammatory response involves the production and release of inflammatory modulators that function to both destroy damaged cells and heal injured tissue. In order to perform this function, however, various inflammatory modulators either directly produce and/or signal the release of agents that produce reactive oxygen species for the purpose of destroying invading agents and/or injured cells. The inflammatory response, therefore, involves a balance between the destruction of damaged cells and the healing of injured tissue, since an imbalance can lead to oxidative stress and the onset of various inflammatory disease pathologies.
One manifestation of the inflammatory process in the body is edema, the term “edema” referring to the accumulation of excess fluid within body tissues. Not all edema, however, has been established as caused by or associated with inflammation. Edema may be systemic in nature (as in congestive heart failure, renal failure, or pulmonary edema) or localized. Localized edema generally involves swelling of the arms or legs, with lower leg edema particularly common. The effects of localized edema are well known. Patients can be somewhat to significantly disabled, as a substantial volume of fluid can accumulate in the affected limb or limbs. Normal, everyday activities can become severely limited. Elderly people are particularly susceptible to development of localized edema, since the elderly frequently suffer from medical conditions in which blood flow is limited or decreased, and/or take medications that can give rise to edema. The most common reason for edema in many people is chronic venous insufficiency.
Although treatment of the underlying pathology, if such treatment is possible, will normally reduce edemic swelling, treatment is often unavailable or only partially effective. Lymphedema, for example, is a chronic condition that cannot be cured. One solution that is used in alleviating edema, particularly in the management of lymphedema, is compression therapy. That is, the swollen limb is wrapped and compressed to reduce and/or disseminate the localized, accumulated fluid. For example, the ReidSleeve® (Peninsula Medical, Inc.) is a compression device formed of a flexible synthetic material which is strapped on to a patient's limb at the site of swelling and then tightened (see U.S. Pat. Nos. 5,904,145, 5,916,183, and 5,196,231 to Reid). See also U.S. Pat. No. 5,759,164 to Pacey and U.S. Pat. No. 5,830,164 to Cone et al., both of which also describe devices for applying pressure to an edemic limb. The use of such compression bandaging has provided some beneficial results to patients, but is potentially harmful unless the amount of pressure applied is carefully controlled and regularly monitored. Otherwise, application of significant pressure can exacerbate the patient's condition or cause additional problems, by excessively reducing or even blocking blood circulation. While these types of devices can be safely and effectively applied by the medical practitioner, once the patient is home and applying the compression sleeve without guidance, its use becomes risky.
Pharmacological agents have also been proposed for use in treating localized edema; such agents are typically selected from those drugs normally used in the treatment of generalized inflammation, e.g., NSAIDs such as aspirin, ibuprofen, and the like, corticosteroids, and antihistamines. These agents can provide some degree of improvement, but relief is often minimal and short-lived. There are no known treatments that provide significant and lasting relief from localized edema.